Data centers, whether large or small, have a high power consumption which increases the total cost of ownership and contributes significantly to an organization's carbon footprint. The workload of a data center typically shows a diurnal variation with peak and trough periods, but the power consumption is proportional to the peak load that the system is provisioned for and not proportional to the system load at a particular time (which is referred to as ‘power proportionality’). Power management features for server CPUs (central processing units), such as dynamic voltage scaling, can be used to reduce power consumption significantly during troughs in an attempt to make a system more power proportional. Storage is, however, not power proportional and this limits the power proportionality of the whole data center.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known data centers and their storage systems.